I think it also reinforces console's centrality in 3rd party / PC compatibility area, even if compatibility with base spec is still aimed for,
devs can free their concepts to work more ideally on higher "pro" spec, keeping the gulf more tolerable as far as PC gaming goes
(where of course only minority actually high spec gaming rigs, and mass market depends on lower spec compatibility for sales volume)

There were different motivations this gen.

Sony made Pro for 4K and PSVR, mainly to hinder their users from flocking to PCs.

Microsoft made the X1X to prevent losing even more fans to Sony.

Assuming both will invest in VR next gen and the VR market will grow considerably larger, we could well see VR and possibly ray tracing to be driving factors mid gen. 

Winner can mock the loser directly after death only on VGC, but can only target the surviving family on social media.

I seriously hope it is not very 3yr refresh like PC gaming. Microsoft has hinted this and I personally hate this idea. Even a decent PC can last 5yrs as they have option of various settings and resolution.

YOu don't need to upgrade every 3 years on PC though.

True. But realistically there is only one way for any of this to be possible.

Take for instance a game console has a budget of $500. That $500 must cover everything that goes into that box...... including the controller. Now say $150 is spent on the APU and another $150 on RAM. The only way to get performance gains is if for that same amount of money you can get more hardware.

Ideally, node shrinks mean two things. You can either get the same performance but from using less silicon to build the chips thanks to your node shrink  and spend less money (slim consoles) or you use the same amount of silicon as before but have more transistors due to the node shrink and as a result better performance (Pro/X) all the while spending the same amount you originally started with.

There may be slight benefits here and there like maybe a doubling or ram module capacity so you only need half the mount of modules as you originally did but thas pretty much it.

The key thing here though is that how the APU is built remains the same. Those alternatives you are talking about while being able to make a more powerful APU will also mean a more complicated APU design wise which will result in costs being higher than the original launch costs to begin with. Thats a no no.

The pro and X exist because spending $120 in 2016 got them an APU that was way more powerful than the one that $120 got them in 2013. Still about the same sized APU. About the same cost. Just were ale to fit more transistors in the same space while using the same manufacturing process.

I hope so. I love my Pro and my X. In fact I would be fine with them releasing upgrades at both 5nm and 3nm. Give me new optional upgrades every other year, and games built with dynamic frame rate and resolution, so they can automatically take advantage of improved hardware. I would love to see the console space offer options from entry level to enthusiast level equipment, just like we have in Music and Video equipment. Like I've said for a long time, I would love to see something like a $399.99 Base Model, a $799.99 mid range model, and a $999.99 Premium model. Let us pay for the level of expereince we want. Give us an option for the best gaming performance, without being forced to go to PC.

I'd say that if Microsoft's motivations were solely on prevention of fans picking up a ps4, they'd have launched their 2016 version of the X and not given the pro and Sony a year alone in the "premium" home console space.

It's equally about momentum. Having a product that's the "best" and having a different product image heading into next generation. Resolution-gate was massive. It's not happening again any time soon.

It's certainly possible but you have to remember that this generation the mid-cycle upgrades were a way to keep up with the fact that many people now have 4K displays and are keen to use them for gaming. Next time around the resolution of mainstream tvs will not exceed 4K during the lifespan of the console so I think it's more than likely a company like Sony will release a $500US beast that hits about 10-12 teraflops and can handle 4K with ease and then try to milk 7-8 years out of that sucker...

Sony most likely, Xbox probably not. Due to Cloud Streaming and if the rumours are true, there wont be any reason to make a mid console upgrade.